Allah (سبحانه و تعالى) has instructed Muslims to send
salawat on Prophet Muhammad (ﷺ) as it was revealed in the Qur'an, Surah al-Ahzab (33), Ayah 56:
إِنَّ ٱللَّٰهَ وَمَلَائِكَتَهُ يُصَلُّونَ عَلَىٰ ٱلنَّبِيِّ يَا أَيُّهَا ٱلَّذِينَ آمَنُوا۟ صَلُّوا۟ عَلَيْهِ وَسَلِّمُوا۟ تَسْلِيمًا
"Allah and His Angels send blessings on the Prophet, O you who believe! Send your blessings on him, and salute him a thorough salutation"
Sending salawat upon Prophet Muhammad (ﷺ) and his family paves way for his intercession on the judgement day.
ٱللَّٰهُمَّ صَلِّ عَلَىٰ مُحَمَّدٍ وَعَلَىٰ آلِ مُحَمَّدٍ